Gear pump and motor having a sealed lock for preventing hydraulic oil from leaking between the ends of the teeth of the gears

ABSTRACT

A gear pump and motor having a housing, a pair of gears engaged with each other, and a seal block disposed between the inner surface of the housing at high pressure side and the teeth ends of the gears, which has the seal block having a passage formed therethrough for hydraulic oil, a plurality of pressure chambers formed between the inner surface of the housing and the seal block, and a plurality of holes or passage are formed in the seal block for communicating the pressure chamber with the gear side. Thus, it prevents hydraulic oil from leaking to provide a high efficient gear pump and motor.

United States Patent 1191 Futamata et a1.

1451 Oct. 1, 1974 THE GEARS Inventors: Masayuki Futamata, Tokyo; TakaoNukada; Yasuo Kitta; Koiti Morita; Kazuyuki Hirose, all of Yokohama,Japan Assignee:

Filed:

Kabushiki Kaisha Komatsu Seisakusho, Tokyo, Japan Dec. 21, 1972 Appl.No.: 317,707

Foreign Application Priority Data [56] References Cited UNITED STATESPATENTS 1,058,153 4/1913 Clark 418/71 3,472,170 10/1969 Eckerle 418/126Primary Examiner-John .1. Vrablik Attorney, Agent, or Firm-Armstrong,Nikaido & Wegner 5 7 ABSTRACT A gear pump and motor having a housing, apair of gears engaged with each other, and a seal block disposed betweenthe inner surface olf the housing at high pressure side and the teethends of the gears, which has the seal block having a passage formedtherethrough for hydraulic oil, a plurality of pressure cham- Jan. 24,1972 Japan 47-8272 betS formed between the inner Sui-fa:e of the housing24, 1972 Japan t 47-9552 and the seal block, and a plurality of holes orpassage 1972 Japan 47953 are formed in the seal block for communicatingthe Jan. 24, Japan t 1 pressure chamber gear ide Thus prevents hydraulicoil from leaking to provide a high efficient UaS- Cl. gear pump andmotor Int. Cl. F011: 19/02, F03c 3/00, F04c 15/00 Field 01 Search418/71, 125, 126, 129 7 Claims, 27 Drawlng Figures PMENTE BBT mm mm WPRIOR ART GEAR PUMP AND MOTOR HAVING A SEALED LOCK FOR PREVENTINGHYDRAULIC OIL FROM LEAKING BETWEEN THE ENDS OF THE TEETH OF THE GEARSThis invention relates to a gear pump and motor. and more particularlyto improve gear pump and motor having a seal block for preventinghydraulic oil from leaking between the teeth ends of the gears.

In the conventional gear pump and motor. a drive gear and a driven gearare engaged in mesh with each other in a housing, and for example. whenthis gear pump and motor is used as a pump, fluid is intaken from aninlet by means of the rotation of the drive and driven gears. and is fedout from an outlet as high pressure (when the gear pump and motor isused as a motor, fluid intaking side becomes high pressure). In order toprevent gap or clearance from being produced at the ends of the gears athigh pressure side and to lessen the area for hearing high pressurefluid, in such type of gear pump and motor, a seal block is so disposedthat the teeth ends of the drive and driven gears are contacted witheach other in the housing at high pressure side.

However, since the conventional seal block of the gear pump and motor issymmetrical with respect to the engaging center of the drive and drivengears, the pressure distribution of hydraulic fluid for acting onto thesurface of the seal block contacting with the drive and driven gears isdifferent at the drive side and at the driven side in every half pitchof the gears. For this reason, the seal block vibrates, or onecontacting portion of the seal block with the gear is worn so that theseal block is displaced to one side. Thus, it is impossible to obtainstable sealing of the teeth ends of the gears of the gear pump andmotor.

More particularly, when the contacting conditions of the contactingportions of the seal block with the teeth ends of the drive and drivengears are different at the drive side and at the driven side, thepressure distribution of hydraulic fluid for acting onto the contactingportion of the seal block at the drive side and the pressuredistribution of hydraulic fluid for acting onto the contacting portionof the seal block at the driven side are different with the result thatone hydraulic pressure becomes higher than the other hydraulic pressureso that there takes place a couple of forces that overall the seal blockrotates along the outer periphery of the seal block. Therefore, thecontacting of the teeth ends of the gear with the contacting portion oflow pressure side becomes stronger than the other with the result thatone side is worn as its disadvantage.

Further, since the width of the seal block is made equal to the width ofthe gears in the conventional gear pump and motor so that thelongitudinal movement of the seal block is affected only by thehydraulic force. if the urging force of the seal block onto the gears isstrong, the seal block is gradually worn by means of the contacting withthe teeth ends of the gears.

This invention contemplates to eliminate the aforementioneddisadvantages of the conventional gear pump and motor, and to provide animproved gear pump and motor.

It is an object of the present invention to provide a gear pump andmotor which may always maintain the contacting of the teeth ends of thegears with the seal block so as to prevent high hydraulic pressure fluidfrom leaking from the teeth ends of the gears.

It is another object of the present invention to provide a gear pump andmotor which may not vibrate the seal block so as to obtain stablesealing of the teeth ends of the gears.

It is a further object of the present invention to provide a gear pumpand motor which may prevent the variation of the seal block.

It is still another object of the present invention to provide a gearpump and motor which may easily produce a pressure chamber so as toimprove the accuracy thereof.

It is still another object of the present invention to provide a gearpump and motor which may improve the endurance thereof.

It is still another object of the present invention to provide a gearpump and motor which may easily balance the hydraulic pressure of theseal block.

One characteristic feature of the present invention is a gear pump andmotor having a housing. a pair of gears engaged with each other, and aseal block disposed between the inner surface of the housing at highpressure side and the teeth ends of the gears, which comprises the sealblock having a passage formed therethrough for hydraulic oil a pluralityof pressure chambers formed between the inner surface of the housing andthe seal block. and a plurality of holes formed in the seal block forcommunicating the pressure chamber with the gear side.

These and other objects, features and advantages of the presentinvention will becomes apparent from the following description taken inconjunction with the accompanying drawings. in which:

FIG. 1 is a longitudinal sectional view of the conventional gear pumpand motor;

FIG. 2 is a schematic view of the conventional gear pump and motor forexplanatory purpose;

FIG. 3 is a longitudinal sectional view of the gear pump and motor ofthe present invention;

FIG. 4 is a sectional view of the gear pump and motor taken along theline IV IV in FIG. 3;

FIG. 5 is an enlarged perspective view of one embodiment of the sealblock used in the present invention;

FIG. 6 is a side view of the seal block showing the state of thepressure distribution acting onto the seal block;

FIG. 7 is a side view of another embodiment of the seal block used inthe present invention;

FIG. 8 is a side view of a further embodiment of the seal block used inthe present invention;

FIG. 9 is a back view of the seal block shown in FIG. 8;

FIG. 10 is a sectional view of another embodiment of the gear pump andmotor of the present invention;

FIG. 11 is an enlarged partial view at the part XI in FIG. 10;

FIG. 12 is an enlarged partial view at the part XII in FIG. 10;

FIG. 13 is a longitudinal sectional view of the essential part of afurther embodiment of the present invention;

FIG. 14 is a plan view of the plate used in this invention;

FIG. I5 is a sectional viewof the plate taken along the line XV XV inFIG. 14;

FIG. 16 is a longitudinal sectional view of still another embodiment ofthe present invention;

FIG. 17 is a front view of the essential part of the present invention;

FIG. 18 is a sectional view taken along the line XVIII XVIII in FIG. I7;

FIG. 19 is a perspective view of the seal plate used in the presentinvention;

FIG. 20 is a plan view of still another embodiment of the seal plateused in the present invention;

FIG. 21 is a sectional view of the seal plate taken along the line XXIXXI in FIG. 20;

FIG. 22 is a sectional view of the seal plate taken along the line XXIIXXII in FIG. 20;

FIG. 23 is a schematic view of the seal plate used in the presentinvention for the explanatory purpose;

FIG. 24 is a side view partially omitted of still another embodiment ofthe present invention;

FIG. 25 is a schematic view of the essential part of the device shown inFIG. 24-;

FIG. 26 is a sectional view taken along the line XXVI XXVI in FIG. 25;

FIG. 27 is a view seen in the direction by an arrow XXVII in FIG. 26.

For the better understanding of the present invention, the conventionalgear pump and motor will now be described with reference to FIGS. I and2.

As shown in FIG. I, in the conventional gear pump and motor, a drivegear 2 and a driven gear 3 are engaged in mesh with each other in ahousing I, and for example, in the event that this gear pump and motoris used as a pump, fluid is intaken from an inlet 4 by means of therotation of the drive and driven gears 2 and 3, and is fed out from anoutlet 5 as high pressure (when the gear pump and motor is used as amotor, fluid intaking side becomes high pressure). In order to preventgap or clearance from being produced at the ends of the gears 2 and 3 athigh pressure side and to lessen the area for bearing high pressurefluid in such type of gear pump and motor, a seal block 6 is so disposedthat the teeth ends of the drive and driven gears 2 and 3 are contactedwith each other in the housing I at high pressure side.

However. since the conventional seal block 6 of the gear pump and motoris symmetrical with respect to the engaging center of the drive anddriven gears 2 and 3 as shown in FIG. 1, the pressure distribution ofhydraulic fluid for acting onto the surfaces 6a and 6b of the seal block6 contacting the drive and driven gears 2 and 3 is different at thedrive side and at the driven side in every half pitch of the gears 2 and3, as shown in FIG. 6. Therefore, the seal block 6 vibrates, or onecontacting portion 6a or 6b of the seal block with the gear is worn sothat the seal block 6 is displaced to one side. Thus, it is impossibleto obtain stable sealing of the teeth ends of the gears 2 and 3 of thegear pump and motor.

Further, when the contacting conditions of the contacting portions 6aand 6b of the seal block 6 with the teeth ends of the drive and drivengears 2 and 3 are different at the drive'side and the driven side. thepressure distrubution of hydraulic fluid for acting onto the contactingportion of the seal block 6 at the drive side and the pressuredistrubution of hydraulic fluid for acting onto the contacting portionof the seal block 6 at the driven side are different with the resultthat one hydraulic pressure becomes higher than the other hydraulicpressure so that there takes place a couple of forces that overall theseal block 6 rotates along the outer periphery of the seal block 6.Therefore. the contacting of the teeth ends of the gear with thecontacting portion of low pressure side becomes stronger than the otherwith the result that one side is worn.

Then. since the width of the seal block 6 is made equal to the width ofthe gears 2 and 3 in the conventional gear pump and motor as shown inFIG. 2 so that the longitudinal movement of the seal block 6 is affectedonly by the hydraulic force. if the urging force of the seal block 6onto the gears is strong. the seal block 6 is gradually worn by means ofthe contacting with the teeth ends of the gears 2 and 3.

Reference is now made to FIGS. 3 to 5. which show one embodiment of thegear pump and motor of the present invention.

A seal block 6 is disposed between the inner surface 8 of a housing 1 athigh pressure side and the teeth ends 10 and 12 of gears 2 and 3 engagedwith each other. and has a chamber 14 formed therethrough for hydraulicoil. and pressure chambers I6 are formed between the inner surface 8 ofthe housing 1 and the seal block 6. Holes or passages 18 are formed inthe seal block 6 for communicating the pressure chamber 16 with the gearside.

The seal block 6 is so formed as to be the same width that of the gears2 and 3. and the housing is composed of a body 1a and a cover Ibconnected by bolts 20. Numeral 22 represents an inlet, and 24 representsan outlet. Seal rubbers 34 and backup plates 36 are provided in thepressure chamber 16 for preventing high pressure hydraulic oil fromleaking from the contacting surfaces of the inner surface 8 of thehousing 1 and the seal block 6. The drive gear 2 is journalled with adrive shaft 26, and the driven gear 3 is journalled with a driven shaft28. The shafts 26 and 28 are rotatably mounted to the housing I throughbearings 30. Numeral 32 represents circular side plates which aredisposed between the gears 2, 3 both ends of the seal block 6 and theinner surface of the housing 1, respectively. A hole 38 is formed in theside plate 32 to communicate with the chamber 14. The side plate 32 isalways urged in contact with the gears 2 and 3 and the both ends of theseal block 6 by high pressure hydraulic oil introduced between the innersurface of the housing I and the side plate 32, that is, by thehydraulic pressure in the chamber 14, so as to prevent the hydraulic oilfrom leaking from the gears 2 and 3 and both ends of the seal block 6.In the drawings, movable type side plate (push type) is shown, butstationary type side plate may also be used within the scope of thisinvention.

It should be understood from the foregoing description that since thepressure chamber 16 is formed at the seal block 6 to be communicatedwith the gear side through the holes 18 as this is used as a pump, theseal block 6 is always urged in the direction to contact with the teethends 10 and 12 of the gears 2 and 3 by the discharge pressure of thehydraulic oil at high pressure side, and even if the discharge pressurebecomes high so that the gears 2 and 3 are moved to low pressure side orintake side in case of pump, since the seal block 6 moves followed bythe movement of the gears 2 and 3, the contacting of the teeth ends 10and 12 of the gears 2 and 3 with the seal block 6 may be always keptconstant, and accordingly it is possible to prevent high pressure fluidfrom leaking from the teeth ends 10 of the gears 2 and 3. Further, sinceit has less part acting with the high pressure. it is possible to reducethe hearing load at the same time to reduce the thickness of thehousing.

Referring now to FIGS. 6 and 7, another embodiment of the seal blockused in the gear pump and motor of the present invention will now bedescribed.

As shown in FIG. 7, the seal block 6 is so formed as to be asymmetricalwith respect to the engaging center of the gears 2 and 3 in such amanner that the contacting portions 6c and 6d of the seal block 6 withthe gears 2 and 3, respectively are displaced by half pitch of the gearsin circumferential direction of one gear. However, the length of arcuateof the contacting portions 6c and 6d are equal, and its length isslightly longer than the length of one pitch of the gear plus the widthof the teeth ends.

Thus, the contacting state of the contacting portion 60 of the sealblock 6 and the drive gear 2 becomes the same as the contacting state ofthe contacting portion 6d of the seal block 6 and the driven gear 3 sothat the pressure distrubution acting onto the contacting portions 60and 6d becomes equal, as shown in FIG. 7. This pressure distrubution isvaried as the teeth ends moves, but becomes equal at both contactingportions 60 and 6d.

It should be understood that since the contacting portions 60 and 6d ofthe seal block 6 are displaced by half pitch of the gear in phase at thedrive side and at the driven side, the pressure acting onto bothcontacting portions 6c and 6d becomes equal, and accordingly the sealblock does not vibrate, nor a couple of forces act to the seal block 6,but the seal block is held in stationary state thereby providing alwaysstable sealing of the teeth ends.

Reference is now made to FIGS. 8 and 9, which show a further embodimentof the seal block used in the gear pump and motor of the presentinvention. As shown in FIG. 8, holes 42a and 42b are formed from thecontacting portions 6a and 6b of the seal block 6 toward the center ofthe seal block 6 in such a manner that both holes 42a and 42b arecrossed at their ends so as to communicate the contacting portions 6aand 6b with the holes 42a and 42b. The opened position of the holes 142a and 421; are symmetrically disposed at the contacting portions 6aand 6b of the seal block 6, and are disposed substantially intermediatein arcuate direction of the contacting portions. And, as shown in FIG.9, the lateral position of the holes 420 and 42b are any place at rightand left position of the passage 14 of the seal block 6.

Thus, the contacting portion 6a contacting with the drive gear 2 and thecontacting portion 6b contacting with the driven gear 3 are communicatedwith each other through the holes or passages 42a and 42b so that thepressure acting onto the contacting portions 6a and 6b of the seal block6 becomes equal.

Although the holes 42a and 42b are formed in the seal block 6 in theabove embodiment, they may be formed on the side surface of the sealblock 6 as grooves so as to communicate with the contacting portions 6aand 612, or grooves may be provided on the side plate 32. In this case,it is necessary that both side surfaces must be cut to form grooves sothat the thrust force may not act onto the seal block 6.

It should be understood that since both the contact ing portions 6a and6b of the seal block 6 with the gears 2 and 3 are communicated with eachother by the holes 42a and 42b, the pressure distribution acting ontoboth contacting portions 6a and 6b becomes equal. and accordingly acouple of forces may not act onto the seal block 6, but stable sealingof the seal block 6 with the teeth ends of the gears 2 and 3 may beconducted.

Referring now to FIGS. 10 and 12, which show still another embodiment ofthe gear pump and motor of the present invention, on the outer surfaceof the seal block 6 are formed pressure chambers 16a, 16b and I60. Thecenter pressure chamber 16b is communicated between the gears 2 and 3through the passage I4, and a stepped portion 44 is formed at theopening of the pressure chamber 1612 at the passage 14, and a collar 46is engaged at the outlet 22 of the housing 1 to be inserted into thestepped portion 44 so as to from a throttle 48 with the collar 46 andthe stepped portion 44. The pressure chambers 16a and 160 arecommunicated between the gears 2 and 3 through holes 18a and 181;,respectively, and throttles 50 and 52 are formed at the holes 180 and18h, respectively. O-rings 54 are engaged with the pressure chambers16a, 16b and 16c to be urged onto the inner peripheral surfaces of thehousing 1.

When the seal block 6 moves in X direction, the volume of the pressurechambers 16a, 16b and 16c becomes smaller,'and accordingly the hydraulicoil tends to flow through the throttles 50, 48 and 52 and holes 18a, 14and 18b toward the gear side. but the hydraulic pressure in the pressurechambers 16a, 16b and 160 becomes higher than the pressure at the gearside by the flow resistance of the trottles 50, 48 and 52 so as to prevent the seal block 6 from moving in X direction.

On the other hand, when the seal block 6 moves in X direction, thevolume of the pressure chambers 16a, 16b, and 16c becomes larger, andaccordingly the hydraulic oil tends to flow from the gear side throughthe V holes 18a, 14 and 18b toward the pressure chambers 16a, 16b and16c. and therefore. the hydraulic pressure at the gear side becomeslower than the pressure of the pressure chambers 16a, 16b and [Ge so asto prevent the seal block 6 from moving in X direction.

It should be understood that since the throttles 50, 48 and 52 areprovided in the holes 18a, 14 and 18b for communicating the pressurechambers 16a, 16b and 160 on the outer surface of the seal block 6between the gears 2 and 3, the force of restitution takes place in thedirection opposite to the moving direction of the seal block 6 againstthe movement of the seal block 6, and accordingly the variation of theseal block may be prevented.

Referring now to FIGS. 13 to 15., which show still another embodiment ofthe gear pump and motor of the present invention, the seal block 6 iscomposed of a seal block body 6c and a plate 6f. More particularly, theseal block body 6c has holes 18a, 14 and 18b therethrough, and the plate6f also has holes 56, 58 and 60 and is bent along the outer surface ofthe seal block body 6c. This plate 6f is so disposed in the housing 1 asto be superimposed on the outer surface of the seal block body 6e insuch a manner that the holes 56, 58 and 60 form pressure chambers 116a,16b and together with the outer surface of the seal block body 60.O-ring 54 are disposed in the pressure chambers 16a, 16b and 16c.

FIG. 16 shows still another embodiment of the gear pump and motor ofthis invention, and the pressure chambers 16a, 16b and 160 are formed onthe inner surface of the plate 6ftogether with the outer contactingsurface of the seal block 6, and a hole 62 is formed in the pressurechatnher 16/) at the center thereof. and the outer surface of the plate6/ is slidingly contacted with the inner peripheral surface of thehousing I.

It should be understood that since the seal block 6 is composed of theseal block body 6e having the holes 18a, l4 and 180, and the plate 6fhaving the pressure chambers 16a, 16b and 16c opposite to the holes 18a,14 and 18b in contact with the outer surface of the seal block body 62,and accordingly the plate 6]" is simply constructed in such a mannerthat only holes are formed at the plate and the plate 6f is bent alongthe outer surface of the seal block body 6e, the pressure chambers arevery easily formed so as to improve the accuracy thereof.

Reference is now made to FIGS. 17 to 23, which show still anotherembodiment of the gear pump and motor of the present invention.

In this embodiment, the pressure chambers 16a, 16b and 160 are formed onthe outer surface of the seal block 6, and are communicated between thegears 2 and 3 through the holes 18a, 14 and 18b. As shown in FIG. 17,these pressure chambers 16a, 16b and 160 have the same length of thewidth as the width of the seal block 6, and seal plates 64 of the samelength as the total length of the pressure chambers 16a and 160 areengaged slidably in the pressure chambers 16a and 16c. As shown in FIGS.20 to 22, the seal plate 64 may have a recess 66 at the inside surface,or as shown in FIG. 19, it may be of planar shape. A seal plate 70formed with a hole 68 therethrough is slidably engaged at the center inthe pressure chamber 16b.

In such a structure, hydraulic oil between the gears 2 and 3 acts to thepressure chambers 16a, 16b and 160 through the holes 18a, 14 and 18bwith the result that the seal plates 64 and 70 are urged onto the innerperipheral surfaces of the housing 1. At this time, the seal block 6 ismoved laterally of the drawing, and there are produced gaps between theseal block 6 and the inner peripheral surface of the housing 1, andaccordingly high pressure hydraulic oil tends to flow to the endsurfaces 6g of the seal block 6 from the gap of the pressure chambers16a, 16b and 160, but since the end surfaces 6g are urged by the sideplates 32, the hydraulic oil cannot flow out therefrom.

It should be understood that since the present invention comprises theseal block 6 formed with the pressure chambers 16a, 16b and 160 havingthe same length as the width of the seal block on the outer surfacethereof, seal plates 64 having the same length as the length of thepressure chambers 16a, and 160 and slidably engaged with the pressurechambers l6a, and 16c, seal plate 70 having the same length as thelength of the pressure chamber 16/), and a hole 68 at the center thereofand slidably engaged with the pressure chamber 16b, and side plates 32contact at both ends of the seal plates 64 and 70, the pressure chambermay be formed along all the width of the seal block in comparison withthe pressure chamber containing the O-rings and backup rings as theforegoing embodiment so that the working is easy so as to provide easilyaccuracy, and since the seal plate is used instead of O-ring, itsbreakage is less so as to improve its endurability.

Referring now to FIGS. 24 to 27, which show still another embodiment ofthe gear pump and motor of the present invention, collar 6h is projectedfrom both sides of the outer surface of the seal block 6. and grooves74. 76 and 78 are formed on the outer surface of the seal block 6. andthe groove 76 are communicated through a hole 80 between the gears 2 and3. Side plates 82 are provided at both side surfaces of the seal block 6in such a manner that clearance t is provided between the peripheralsurface 82a ofthe side plates 82 and the collar 611.

When the gear side 6/ of the seal block 6 is contacted with the teethends of the gears 2 and 3 to be worn. the collar 6/1 contacts with theperipheral surface 82a of the side plate 6 so that the seal block 6 doesnot move to the gear 2 and 3 side so as to prevent the seal block 6 fromwearing.

It should be understood that since the collar 6/1 is formed on bothsides of the outer surface of the seal block 6 so that clearance r isprovided between the pe ripheral surface 82a of the side plates 82disposed at both sides of the seal block 6 and the collar 6/2. the wearby the contact of the seal block 6 with the gears 2 and 3 is preventedby contacting the collar 6/2 with the side plates 82 so as to improvethe endurability and it is easy to provide hydraulic balance of the sealblock.

What is claimed is:

1. A gear pump or motor having a housing including an inner and outersurface and at least two ports communicating between the interior andexterior thereof providing an inlet and outlet for the pump or motor; apair of gears engaging each other within a portion of said housing; anda seal block disposed within said housing between the inner surface ofthe housing at the high pressure side thereof and the teeth ends of thegears wherein said seal block includes a first passage communicatingbetween the portion of said housing occupied by said gears and one ofsaid ports; a plurality of pressure chambers formed between the innersurface of said housing and said seal block; and a plurality of secondpassages formed between said pressure chambers and the portion of thehousing occupied by said gears at the periphery of the gears spaced fromthe high pressure engagement area of the gears.

2. A gear pump or motor as set forth in claim 1, wherein a portion ofsaid seal block facing one of said gears is displaced by half the pitchof said gears in the circumferential direction with respect to a portionof said seal block facing the other of said gears.

3. A gear pump or motor as set forth in claim 1, wherein said pluralityof pressure chambers comprise three pressure chambers, the center of thethree pres sure chambers communicates between the gears through apassage, and a stepped portion is formed at the opening of said centerpressure chamber at said passage, and wherein a collar is engaged at theoutlet of said housing, said collar being inserted into the steppedportion to form a throttle therewith. and wherein the side pressurechambers communicate between the gears through holes in which throttlesare formed, and wherein O-rings are engaged with the pressure chambers.

4. A gear pump or motor as set forth in claim 1, wherein said seal blockcomprises a seal block body having holes formed therethrough, and aplate having a plurality of pressure chambers opposite to said holes ofsaid seal block body in contact with the outer surface of said sealblock body.

eluding a collar projecting from both sides of the outer surface of saidseal block. and side plates provided at both side surfaces of said sealblock in such a manner that clearance is provided between the peripheralsurface of the side plates and the collar.

7. A gear pump or motor as set forth in claim I wherein at least onethird passage :is formed in said seal block between said pressurechambers.

1. A gear pump or motor having a housing including an inner and outersurface and at least two ports communicating between the interior andexterior thereof providing an inlet and outlet for the pump or motor; apair of gears engaging each other within a portion of said housing; anda seal block disposed within said housing between the inner surface ofthe housing at the high pressure side thereof and the teeth ends of thegears wherein said seal block includes a first passage communicatingbetween the portion of said housing occupied by said gears and one ofsaid ports; a plurality of pressure chambers formed between the innersurface of said housing and said seal block; and a plurality of secondpassages formed between said pressure chambers and the portion of thehousing occupied by said gears at the periphery of the gears spaced fromthe high pressurE engagement area of the gears.
 2. A gear pump or motoras set forth in claim 1, wherein a portion of said seal block facing oneof said gears is displaced by half the pitch of said gears in thecircumferential direction with respect to a portion of said seal blockfacing the other of said gears.
 3. A gear pump or motor as set forth inclaim 1, wherein said plurality of pressure chambers comprise threepressure chambers, the center of the three pressure chamberscommunicates between the gears through a passage, and a stepped portionis formed at the opening of said center pressure chamber at saidpassage, and wherein a collar is engaged at the outlet of said housing,said collar being inserted into the stepped portion to form a throttletherewith, and wherein the side pressure chambers communicate betweenthe gears through holes in which throttles are formed, and whereinO-rings are engaged with the pressure chambers.
 4. A gear pump or motoras set forth in claim 1, wherein said seal block comprises a seal blockbody having holes formed therethrough, and a plate having a plurality ofpressure chambers opposite to said holes of said seal block body incontact with the outer surface of said seal block body.
 5. A gear pumpor motor as set forth in claim 1, wherein said pressure chambers havethe same the width as the width of said seal block with seal plates ofthe same length as the total length of said pressure chambers engagedslidably in said pressure chambers and wherein a seal plate is formedwith a hole therethrough slidably engaged at the center in anintermediate pressure chamber of said plurality of pressure chambers. 6.A gear pump or motor as set forth in claim 1, including a collarprojecting from both sides of the outer surface of said seal block, andside plates provided at both side surfaces of said seal block in such amanner that clearance is provided between the peripheral surface of theside plates and the collar.
 7. A gear pump or motor as set forth inclaim 1 wherein at least one third passage is formed in said seal blockbetween said pressure chambers.